Relay actuator utilizing a resilient,iron impregnated pad

ABSTRACT

An improvement to an electromagnetic actuator having a coil designed for use with DC current or rectified AC current is provided. The actuator includes an armature mounted for movement in relation to the coil in response to the energization of the coil. A resilient pad impregnated with soft iron particles is provided for directly contacting the pole face of the coil and the armature simultaneously when the armature is actuated by the coil.

United States Patent Prouty [151 3,693,125 Sept. 19, 1972 [54] RELAY ACTUATOR UTILIZING A RESILIENT, IRON IMPREGNATED PAD Robert E. Prouty, Logansport, lnd.

Essex International, Inc., Fort Wayne, lnd.

Filed: Sept. 24, 1970 Appl. No.: 75,078

lnventor:

Assignee:

US. Cl ..335/271, 335/277 Int. Cl ..II011 7/08 Field of Search ..335/248, 277, 270, 271, 276,

References Cited UNITED STATES PATENTS Vassalotti ..335/270 Kreidler ..335/276 3,599,133 8/1971 Richert ..335/230 I 3,389,354 6/1968 Ahlberg ..335/277 X 3,148,313 9/1964 Hancock ..335/27l X 3,384,787 5/1968 Schwartz ..317/123 Primary Examiner-George Harris Attorney-Molinare, Allegretti, Newitt & Witcoff [57] ABSTRACT An improvement to an electromagnetic actuator having a coil designed for use with DC current or rectified AC current is provided. The actuator includes an an mature mounted for movement in relation to the coil in response to the energization of the coil. A resilient pad impregnated with soft iron particles is provided for directly contacting the pole face of the coil and the armature simultaneously when the armature is actuated by the coil.

8 Claims, 5 Drawing Figures PATENTED SEP 19 m 54 I -lull 23 22 I NVEN TOR ROBE/P7 E PROUT) ATTORNEYS RELAY ACTUATOR UTILIZING A RESILIENT, IRON IMPREGNATED PAD BACKGROUND OF THE INVENTION This invention relates generally to an improvement in an electromagnetic actuator. Such actuators generally include a coil mounted on a frame and an armature mounted for movement in relation to the pole face of the coil and biased away from the pole face. When the coil is energized by a source of electrical power, a magnetic field is developed which produces a force tending to attract the armature to the pole face.

One example of the use of such an electromagnetic actuator is in heating and/or air conditioning units. The actuator is turned on by the closing of a pair of contacts when the temperature of the room to be climate controlled varies from a certain predetermined level and is turned off by the opening of the contacts when the temperature of the room returns to the predetermined level. In this and other applications, the armature of the actuator will be moved back and forth many times. Accordingly, it is desirable to provide an electromagnetic actuator which will prevent the generation of impact noise when the armature, actuated by the energized coil, meets the pole face of the coil.

Devices in the prior art have attempted to solve this impact noise problem by various means, such as separating the armature from the pole face by a flexible resilient material.

However, the devices of the prior art have not been successful in eliminating both the noise that is present when the relay first closes and the hum or noise which arises from armature vibration after the impact. It is accordingly desirable to provide such a device which both will dampen impact noise of the armature and at the same time reduce the hum or noise of armature vibratron.

SUMMARY OF THE INVENTION In a principal aspect, the present invention relates generally to an improvement in an electromagnetic actuator of the type having a frame, a relay coil connected to a base of the frame and a pole face projecting from one end of the coil. An armature is mounted for movement in relation to the pole face and biased away from the pole face. The improvement generally comprises a resilient pad impregnated with powdered iron particles and adapted to directly contact both the pole face and the armature simultaneously when the annature is attracted to the pole face in response to the energization of the coil.

In a preferred embodiment, the resilient pad is a silicone rubber disc impregnated with finely powdered iron particles and is connected to the armature adjacent the pole face of the coil so that when the armature is actuated by the energized coil, the impact of the armature against the pole face is cushioned and a continuous flux path between the armature and the pole face is provided so that the armature may be held firmly against the pole face without vibration.

BRIEF DESCRIPTION OF THE DRAWINGS There follows a brief description of the drawings showing a presently preferred embodiment of the present invention wherein like numerals refer to like elements and wherein:

FIG. 1 is a side elevational view of the improved electromagnetic actuator of this invention;

FIG. 2 is a top view of the electrical contacts operated by the armature of the actuator shown in FIG.

FIG. 3 is a perspective view of the disc employed in a preferred embodiment of this invention;

FIG. 4 is an example of a circuit for rectifying current to be supplied to the coil of the actuator shown in FIG. 1; and

FIG. 5 is an alternative embodiment of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT One example of a preferred embodiment of the improved electromagnetic actuator of this invention is shown in FIG. 1. The improved actuator 10 employs a basic design generally similar to that shown in the drawings of US. Pat. No. 2,900,472 entitled Relay and issued to W. F. Dowdle on Aug. 18, 1959.

The actuator 10 includes a frame comprised of an upright rigid member 12 and a horizontal support member 16.

A relay coil 18 is rigidly secured to the frame horizontal support member 16 by means of a screw 20. The coil 18 includes a pole piece or core 22 of ferrous material adapted to readily conduct magnetic flux from the coil 18 and a pole face 23 on the end of the pole piece 22.

A non-conducting bracket 24 is rigidly mounted to the upper portion of the frame upright member 12 by means of rivets 26. An armature member 28 of ferrous material extends through a slot 30 in the frame upright member 12 and is pivotally connected thereto for movement in relation to the coil 18. The armature 28 is biased away from the pole piece 22 of the relay coil 18 by means of a spring 32 connected between the spring mounting bracket 34 and one end 36 of the armature 28. The armature 28 is prevented from moving further away form the pole piece 22 of the coil 18 in response to the biasing force of the spring 32 by an armature abutment member 38 which is connected to the upright member 12 and extends outwardly therefrom.

A second mounting contact actuator 40 is connected to the movable end 42 of the armature 28 by means of rivets 44. Flexible contact springs 46 shown in FIG. 2 are connected to the upper portion of the first mounting bracket 24. Movable contacts 48 are rigidly connected to the contact springs 46. Fixed contacts 50 are rigidly mounted on a contact support 52 integral with the first mounting bracket 24 beneath the movable contacts 48.

When the coil 18 shown in FIG. 1 is not energized, the spring 32 biases the armature 28 and the movable contacts 48 upwardly. Thus, movable contacts 48 are out of electrical connection with the fixed contacts 50. When the coil 18 is energized, a magnetic field is developed inside the coil 18 and is conducted through the pole piece 22. It is this magnetic field which attracts the armature 28 to the pole piece 22 to place the mova-. ble contacts 48 in electrical connection with the fixed contacts 50.

In relays of the prior art an undesirable noise was generated when the armature made contact with the. pole face of the coil. As has been pointed out, cushioning members were known in the prior art devices to limit this impact noise. However, these known devices generally were somewhat complicated to construct. Normally, a magnetic gap was left between the pole face of the coil and the armature which prevented a good, solid contact.

The improved electromagnetic actuator of this invention employs a resilient pad 54 impregnated with finely powdered soft iron particles. As may be seen in the drawing of FIG. 1, this pad 54 is connected to the armature 28 directly above the pole piece 22 of the coil 18. When the armature 28 is attracted to the pole piece 22 by energization of the coil 18, the impact noise of the relay 28 against the core 22 is effectively dampened by the resilient pad 54.

The finely powdered soft iron particles which are impregnated in the pad 54 serve to provide an efiective flux path between the pole piece 22 and the armature 28 so that a complete flux path is provided which extends from the pole piece 22 to the resilient pad 54, through the armature 28, the upright and horizontal support members 14 and 16, respectively, and back to the pole piece 22. As will be more completely described hereafter, this complete flux path insures a magnetic grip between the armature 28 and the pole piece 22 and substantially reduces the vibration noise which otherwise would be present.

In the preferred embodiment of this invention, the resilient pad 54 takes the form of a circular disc as shown in FIG. 3. In the preferred embodiment, the disc 54 is formed of silicone rubber and impregnated with finely powdered iron to a density of 60.3788 grams per cubic inch. The resilient pad or disc 54 of the preferred embodiment is approximately 0.375 inches in diameter and approximately 0.062 inches in thickness. It is of course to be understood that the particular size and shape of the resilient pad 54 may be varied with varying requirements and that the particular ferrous particles and density of the finely powdered iron impregnated in the pad 54 may also be varied consistent with the scope and purpose of this invention.

The improved relay of this invention is particularly suitable for use with coils which are to be energized with a rectified source of power. The circuit diagram shown in FIG. 4 is an example of one type of circuit 56 for rectifying current to be supplied to a coil. This circuit employs an AC source of power 58 having its output terminals 60 connected to a diode bridge 62. The diode bridge 62 provides a full wave rectified source of power to the coil 18 whenever the switch 64 is closed. It will be appreciated that a half wave rectifying circuit also may be utilized for this purpose.

As is well known in the art, the rectified power supplied from the rectifying circuit 56 is not pure DC and pulsating coil currents are supplied from such a circuit to the coil 18. Accordingly, with such a circuit, the magnetic flux flowing through the path of the frame, pole piece 22, resilient pad 54, and armature 28 will vary with the varying current in the coil 18. If an air gap or other non-magnetically permeable medium is located in the flux path, continuous vibration noise may be generated due to the pulsating current in the coil 18. The resilient pad or disc 54 of this invention serves the purposes of: dampening the impact noise of the armature 28 against the core 22; substantially reducing vibration noise, which would otherwise be generated by a precise location of the pad 54 directly over the core 22; and providing a magnetic grip of the armature 28 against the core 22 when the coil is energized. Also, the resilient pad 54 of this invention is simple and inexpensive to install and may be utilized even in presently designed relays.

It should be understood that this invention is not limited to a relay having rectified current supplied thereto, but may also be used with solenoid actuators and other non-relay devices. The improved actuator 10 of this invention may also be used in connection with a coil which is energized by a pure DC power supply such as a battery or the like. When so used, the complete magnetic flux path provided by the resilient pad or disc 54 of this invention still serves to substantially dampen the impact noise of the armature 28 against the core 22, and also to provide a higher voltage drop-out level at which the armature 28 is released from the core 22. It should also be understood that the resilient cushioning pad 54 may be also connected to the pole face 23 of the core 22 rather than to the armature 28 as shown in FIG. 5. In such a device, the beneficial results of this invention are still achieved.

Although in the foregoing there has been described a preferred embodiment of the present invention, it is to be understood that modifications to this embodiment may be made by those skilled in the art without departing from the true spirit and scope thereof as defined by the claims appended hereto.

What is claimed is:

1. An electromagnetic actuator comprising in combination a frame of magnetic material, a core supported on said frame, said core having a pole face extending from one end thereof, an armature mounted for movement in relation to said pole face and biased away from said pole face, and a resilient pad having a cross-sectional shape substantially conforming to the cross-sectional shape of said pole face impregnated to a predetermined density with ferrous particles, said pad being connected to said armature and positioned adjacent said pole face such that said pad directly contacts said armature and said pole face simultaneously when said armature is attracted to said pole face in response to a magnetic field from said core to provide a continuous, low reluctance flux path between said armature and said pole face.

2. An electromagnetic actuator as set forth in claim 1 wherein said actuator is adapted for use with a rectified source of energizing power.

3. The improvement in an electromagnetic actuator as set forth in claim 1 wherein said resilient pad is a silicone rubber disc.

4. The improvement in an electromagnetic actuator as set forth in claim 1 wherein said ferrous particles are powdered iron particles.

5. In an electromagnetic relay, a magnetic frame, a core connected to said frame, said core having a pole face extending from one end thereof, and an armature mounted for movement in relation to said pole face and biased away from said pole face, an improvement comprising:

a resilient pad having a shape substantially conforming to the shape of said pole face impregnated to a predetermined density with ferrous particles said use with a rectified source of energizing power.

7. The improvement in an electromagnetic relay as set forth in claim 5 wherein said resilient pad is a silicone rubber disc.

8. The improvement in an electromagnetic relay as set forth in claim 5 wherein said ferrous particles are powdered iron particles;

I I I i 

2. An electromagnetic actuator as set forth in claim 1 wherein said actuator is adapted for use with a rectified source of energizing power.
 3. The improvement in an electromagnetic actuator as set forth in claim 1 wherein said resilient pad is a silicone rubber disc.
 4. The improvement in an electromagnetic actuator as set forth in claim 1 wherein said ferrous particles are powdered iron particles.
 5. In an electromagnetic relay, a magnetic frame, a core connected to said frame, said core having a pole face extending from one end thereof, and an armature mounted for movement in relation to said pole face and biased away from said pole face, an improvement comprising: a resilient pad having a shape substantially conforming to the shape of said pole face impregnated to a predetermined density with ferrous particles said pad being connected to said pole face adjacent said armature for directly contacting both said armature and said pole face when said armature is attracted to said pole face in response to a magnetic field from said core, said pad providing a continuous low reluctance flux path between said armature and said pole face.
 6. The improvement of an electromagnetic relay as set forth in claim 5 wherein said actuator is adapted for use with a rectified source of energizing power.
 7. The improvement in an electromagnetic relay as set forth in claim 5 wherein said resilient pad is a silicone rubber disc.
 8. The improvement in an electromagnetic relay as set forth in claim 5 wherein said ferrous particles are powdered iron particles. 